it's 5% so you can go down to 4.75V an be OKLast night I played for 3 hours and the psu didn't really change at all it stayed in the same numbers it didn't go from like 12 to 13 or 5 to 4 it stayed the same but is it ok for the 5v is at 4.950
Yes , i believe its coil whineI'd still run the PSU under load and check that the voltages don't go outside 5%.
Ahhmmed heard your video and he thinks it's coil whine.....so I'm thinking it probably is.